1. Technical Field
The present disclosure relates to a power MOSFET in particular, to a trench power MOSFET having low on-state resistance and high breakdown voltage and a manufacturing method thereof.
2. Description of Related Art
Power Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) are voltage-controlled devices. Power MOSFETs generally have vertical and horizontal structures, which are well known in the art. Power MOSEFTs have advantages of fast switching, good high frequency performance, high input impedance, and relatively low driving power. Power MOSFETs have been widely utilized in switching applications for power equipment such as power supplies, rectifiers, or low voltage motor controllers. Currently, most of power MOSFETs adopt vertical structure for increasing the component density.
The operation loss of power MOSFETs includes the switching loss and the conduction loss, wherein the on-state resistance (Rds) of the power MOSFETs in conduction is one of the important parameters in determining the operation loss of power MOSFETs. It is well known in the art, that the smaller the on-state resistance, the lower the conduction loss, therefore the lower the power consumption. The on-state resistance of a power MOSFETs is directly proportional to the thickness of the drift region, i.e., the on-state resistance can be reduced by reducing the thickness of the drift region. However, by reducing the thickness of the drifting region, also reduces the breakdown voltage which affects the voltage withstand capability of the power MOSFETs.